Resist roughness improvement by a chemical shrink process

In this paper, we will discuss the improvement of resist pattern roughness on NTD (Negative Tone Development) resist by chemical shrink process. Chemical shrink process is one of the most practical approaches to achieve small feature size CH (Contact Hole) or trench with ArF immersion lithography. We found that this shrink material has not only general benefits of shrink process like DOF (Depth of Focus) margin improvement, but also demonstrates a pattern smoothing effect through observation of the surface of shrink layer using SPM (Scanning Probe Microscope). Additionally, an improvement of LWR (Line Width Roughness) over 16% and an improvement of LCDU (Local Critical Dimension Uniformity) around 60% were observed.